Screen Time Sleep Impact Calculator
Estimate how your phone, laptop, and TV time before bed delays sleep and erodes its quality.
Sleep onset delay
+13 min
Melatonin reduction
−8%
Quality loss
−5%
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Frequently asked questions
Why does screen time hurt sleep?+
Bright blue-rich light suppresses melatonin by up to 50%, delaying sleep onset by 30–60 minutes.
Do night-mode filters fix it?+
Partially. Color temperature shift helps a bit; brightness and stimulating content remain bigger problems.
How long before bed should I stop screens?+
60–90 minutes is ideal. Even 30 minutes of darkness before bed measurably improves sleep onset.
How much light is enough to suppress melatonin?+
As little as 10 lux from a screen close to your eyes can suppress melatonin by 20–30%. Phones held at reading distance commonly exceed 40 lux.
Are e-readers like Kindle better than phones?+
Yes — front-lit e-ink screens emit ~10x less blue light than phones or tablets and don't trigger the dopamine loops of social apps.
Do blue-light blocking glasses really work?+
Amber-tinted (orange) glasses worn 2–3 hours before bed reduce melatonin suppression measurably. Clear 'computer glasses' have minimal effect on sleep.
What's the best evening lighting?+
Dim, warm (<2700K), and below eye level. Aim for under 50 lux at eye level in the last hour before bed — similar to candlelight.
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